Widal / Typhoid Test (Typhidot)

Clinical definition of the Widal / Typhoid test
Typhoid fever or enteric fever is an acute, life threatening and fever causing illness transmitted by the ingestion of food or water that has been contaminated with the feces of a person infected with the bacteria Salmonella typhi or S. paratyphi.  Typically typhoid is accompanied by diarrhea, progressive fever and rose colored rashes. There are two commonly used screening tests which detect antibodies to the bacterium. These are

  • Widal Test
  • Typhidot Test

The Widal test is both quantitative as well as qualitative and it can tell the titres of specific antibodies. The typhidot separately identifies IgM and IgG antibodies against the bacteria. IgM shows recent infection where as IgG signifies remote infection. The Typhidot test only gives result as positive or negative.

Why is the Widal / Typhoid test done?
The typhoid screening test is a used for detection, diagnoses & screening of the fever and other salmonella infections. It detects the antibodies against the infection.

What are the common signs/symptoms when the Widal / Typhoid test is done?
Typhoid fever is characterized by

  • Slow progressive fever as high as 40 °C (104 °F)
  • Profuse sweating
  • Gastroenteritis
  • Non-bloody diarrhea
  • Rash of flat, rose-colored spots (less commonly)
  • Relatively abnormal slow heart beat
  • Malaise
  • Headache
  • Cough
  • Distended abdomen
  • Enlarged spleen and liver
  • Intestinal hemorrhage in severe cases

Who should do the Widal / Typhoid test (Target population)?
Persons suffering from the above signs and symptoms, typically characterized by progressive fever and those who are at a high risk of contracting the infection due to contaminated food and water.

What should I do before the Widal / Typhidot test?

Specimen type

Specimen collection procedure

Preparatory instructions before the test *

Serum (Blood Sample)

Venipuncture - Collection of blood from a vein, usually from the arm.

No Fasting Required.

No other special preparations required.

*Subjects suffering from any illness or on oral or injectable medications are advised to consult their physician prior to requesting any tests or procedures.

How do I interpret my Widal / Typhoid test results?

Reference Range*

Interpretation

Widal

Typhidot

No agglutination

No infection

Negative

No infection

‘*A Reference range is a set of values which helps the healthcare professional to interpret a medical test. It may vary with age, gender, and other factors. Reference ranges may also vary between labs, in value & units depending on instruments used and method of establishment of reference ranges’

Inference: The Widal test is not a very specific test, since patients are often exposed to other bacteria (e.g. Salmonella enteritidis, Salmonella typhimurium and some types of E. coli) in this species that induce cross-reactivity; many people have antibodies against these enteric pathogens, which also react with the antigens in the Widal test, causing a false-positive result. Test results need to be interpreted carefully in the light of past history of enteric fever, typhoid vaccination, and the general level of antibodies in the populations in endemic areas of the world.
An antigen titer of more than 1:80 indicates an active infection. A single Widal test is of little clinical relevance due to the number of cross-reacting infections, including malaria.Demonstration of rising titres is a confirmatory.

Diseases/conditions related to the Widal / Typhoid test

  • Malaria
  • Dengue

Other tests related to the Widal / Typhoid test

  • Malarial parasite smear
  • Dengue test

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Widal (Serum)

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